On Fri, Oct 06, 2017 at 03:50:59PM +0300, Adrian Hunter wrote:
> The default D3 cold delay of 100 ms can cause pauses when streaming audio
> from eMMC.
>
> Intel BYT-related host controllers do not need PCI D3 delays. Although the
> delays can be set to zero via an ACPI _DSM, unfortunately that is not being
> used in all cases. So just set the delays to zero in the driver.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
> drivers/mmc/host/sdhci-pci-core.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
> index 5f3f7b51299f..14ef99b6e5b7 100644
> --- a/drivers/mmc/host/sdhci-pci-core.c
> +++ b/drivers/mmc/host/sdhci-pci-core.c
> @@ -592,9 +592,18 @@ static void byt_read_dsm(struct sdhci_pci_slot *slot)
> slot->chip->rpm_retune = intel_host->d3_retune;
> }
>
> -static int byt_emmc_probe_slot(struct sdhci_pci_slot *slot)
> +static void byt_common_setup(struct sdhci_pci_slot *slot)
> {
> byt_read_dsm(slot);
> +
> + /* PCI D3 delays are not needed */
> + slot->chip->pdev->d3_delay = 0;
> + slot->chip->pdev->d3cold_delay = 0;
The fact that it doesn't need D3 delays sounds like a property of the
device itself, regardless of which (if any) driver claims it.
Can this be done as a quirk instead, maybe something in
arch/x86/pci/fixup.c? Maybe quirk_remove_d3_delay() could be used
directly, or something like pci_d3_delay_fixup()?
> +}
> +
> +static int byt_emmc_probe_slot(struct sdhci_pci_slot *slot)
> +{
> + byt_common_setup(slot);
> slot->host->mmc->caps |= MMC_CAP_8_BIT_DATA | MMC_CAP_NONREMOVABLE |
> MMC_CAP_HW_RESET | MMC_CAP_1_8V_DDR |
> MMC_CAP_CMD_DURING_TFR |
> @@ -649,7 +658,7 @@ static int ni_byt_sdio_probe_slot(struct sdhci_pci_slot *slot)
> {
> int err;
>
> - byt_read_dsm(slot);
> + byt_common_setup(slot);
>
> err = ni_set_max_freq(slot);
> if (err)
> @@ -662,7 +671,7 @@ static int ni_byt_sdio_probe_slot(struct sdhci_pci_slot *slot)
>
> static int byt_sdio_probe_slot(struct sdhci_pci_slot *slot)
> {
> - byt_read_dsm(slot);
> + byt_common_setup(slot);
> slot->host->mmc->caps |= MMC_CAP_POWER_OFF_CARD | MMC_CAP_NONREMOVABLE |
> MMC_CAP_WAIT_WHILE_BUSY;
> return 0;
> @@ -670,7 +679,7 @@ static int byt_sdio_probe_slot(struct sdhci_pci_slot *slot)
>
> static int byt_sd_probe_slot(struct sdhci_pci_slot *slot)
> {
> - byt_read_dsm(slot);
> + byt_common_setup(slot);
> slot->host->mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY |
> MMC_CAP_AGGRESSIVE_PM | MMC_CAP_CD_WAKE;
> slot->cd_idx = 0;
> --
> 1.9.1
>
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